Physical Chemistry

Brown University has a rich tradition in Physical Chemistry, the interdisciplinary research at the crossroads of chemistry and physics. A particular focus of the Chemistry Department is the exploration of chemical reaction dynamics on ultrashort time scales. Using new theoretical and experimental tools, chemical reactions are probed in time increments of 10-14 (0.000,000,000,000,01) seconds!

An exciting new direction in this field of research is the development of new tools that probe the structure of molecules on such short time scales. At Brown, we have a concentration of research programs that is unique in the world. Techniques available at Brown include ultrafast time-resolved methods for electron diffraction, spectroscopy, and x-ray absorption. At the heart of those technologies are multiple ultrashort-pulsed laser systems that set apart Brown’s Chemistry Department, and which provide additional interdisciplinary training opportunities for both graduate and undergraduate students in optics and photonics.

High resolution photoelectron images of phenoxide (C6H5O-) (From the Lai-Sheng Wang lab): “Observation of Mode-Specific Vibrational Autodetachment from Dipole-Bound States of Cold Anions” (H. T. Liu, C. G. Ning, D. L. Huang, P. D. Dau, and L. S. Wang), Angew. Chem. Int. Ed. 52, 8976-8979 (2013).High resolution photoelectron images of phenoxide (C6H5O-) (From the Lai-Sheng Wang lab): “Observation of Mode-Specific Vibrational Autodetachment from Dipole-Bound States of Cold Anions” (H. T. Liu, C. G. Ning, D. L. Huang, P. D. Dau, and L. S. Wang), Angew. Chem. Int. Ed. 52, 8976-8979 (2013).

This experimental prowess is complemented by an equally impressive presence in theoretical chemistry. Theory research groups have been developing models to describe molecular motions, along with computational tools for interpreting the molecular lessons that the new experiments are teaching us. Over the past few years, a particular focus has been the understanding of the fundamental processes behind molecule-to-molecule energy transfer in liquids, and in the interpretation of the new ultrafast techniques developed at Brown and at other institutions.

Attack of a benzene molecule on iron penta carbonyl. (From the Rose-Petruck lab)Attack of a benzene molecule on iron penta carbonyl. (From the Rose-Petruck lab)

Practical applications of research in physical chemistry are numerous. One development may provide a uniquely sensitive and rapid diagnosis of protein shapes. Another involves the application of technologies refined in chemical reaction dynamics research to capture high-resolution, high-contrast images of tissue through the simultaneous applications of x-ray and ultrasound fields. A resolution of several micrometers has already been achieved. In a related collaboration with the Liver Research Center at Brown University, antibodies tethered to x-ray contrasting agents are used to label liver cancer cells in preparation for their x-ray detection.